1. Field of Invention
The present invention relates to a flat light source. More particularly, the present invention relates to a flat light source with high brightness and high illumination uniformity.
2. Description of Related Art
In recent years, liquid crystal display panels (LCD panels) have become the main stream for most display screens. However, since the LCD panel itself cannot emit lights, a back light module has to be provided under the LCD panel to be a light source, so as to display. The light source in the back light module is typically provided by one or more lamps, and the light emitted by the lamp passes through optical films in the back light module and is scattered, such that a surface light source suitable for irradiating the LCD panel is created.
However, if a flat light source can be directly employed, the utilization efficiency of the light can be improved and a more uniform surface light source can be provided, and besides, the flat light source can also be applied in many other fields than as the back light source of LCD panel. Therefore, the flat light source is advantageous in its development.
Generally, the flat light source is a plasma light-emitting element, which emits light through producing high energy electrons by a high voltage difference between the electrode pairs, and then the high energy electrons may bombard the inert gas so as to form the so-called plasma. After that, the excited atoms in the plasma release energy by way of emitting UV, which will then be used to further excite the phosphor in the flat light source, so as to emit visible light.
However, the current flat light source has distinctly lower brightness or presents a non-white color at its peripherals. This is because the light-emitting efficiency of phosphor in the edge of the flat light source is lower than that in the central area. Therefore, the brightness around the flat light source tends to be dimmer.